Field of the Invention
The present invention relates to a sensing method and a magnetometer that measure magnetic field intensity, and particularly, to an optically pumped atomic magnetometer and a magnetic sensing method using electron spin or nuclear spin of atoms.
Description of the Related Art
Optically pumped atomic magnetometers are described in Non Patent Literature 1 (Yosuke Ito, et al., “Magnetic field distribution measurements with an optically pumped atomic magnetometer using a hybrid cell of K and Rb atoms for biomagnetic measurements”, IEICE, Vol. 112, No. 479, MBE 2012-93, p. 31, Mar. 2013) and Patent Literature 1 (Japanese Patent Application Laid-Open No. 2011-203133). The optically pumped atomic magnetometer described in Non Patent Literature 1 includes a cell containing alkali metal gas, a light source for pump beam (pump light, pump light beam) and a light source for probe beam (probe light, probe light beam). The optically pumped atomic magnetometer measures rotation of a plane of polarization of probe beam based on the spin polarization of an atom group rotated by a measurement target magnetic field and polarized by pump beam. Non Patent Literature 1 also illustrates a method of changing an intersection area of probe beam and pump beam in each measurement to separate and measure a magnetic signal of different locations on an optical path of the probe beam. Patent Literature 1 illustrates an example of a magnetic sensor array for emitting probe beam and pump beam to a plurality of cells or each cell.
The intersection area of the probe beam and the pump beam needs to be changed in the optically pumped atomic magnetometer of Non Patent Literature 1, and the magnetic field intensity of different locations on the optical path of the probe beam cannot be measured at the same time. The magnetic field intensity of different locations on the optical path of the probe beam cannot be measured in the optically pumped atomic magnetometer of Patent Literature 1. Furthermore, a detector of signal is necessary for each cell, and there is a problem that the size of the apparatus is increased.
Therefore, the optically pumped atomic magnetometers of Non Patent Literature 1 and Patent Literature 1 cannot separate and measure magnetic information of spatially different places on an optical path of probe beam at the same time by one probe beam.